全文获取类型
收费全文 | 788篇 |
免费 | 62篇 |
国内免费 | 28篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 32篇 |
妇产科学 | 6篇 |
基础医学 | 94篇 |
口腔科学 | 11篇 |
临床医学 | 66篇 |
内科学 | 263篇 |
皮肤病学 | 13篇 |
神经病学 | 22篇 |
特种医学 | 158篇 |
外科学 | 56篇 |
综合类 | 32篇 |
预防医学 | 12篇 |
眼科学 | 5篇 |
药学 | 78篇 |
中国医学 | 6篇 |
肿瘤学 | 22篇 |
出版年
2023年 | 7篇 |
2022年 | 2篇 |
2021年 | 5篇 |
2020年 | 2篇 |
2019年 | 8篇 |
2018年 | 7篇 |
2017年 | 2篇 |
2016年 | 24篇 |
2015年 | 50篇 |
2014年 | 22篇 |
2013年 | 28篇 |
2012年 | 28篇 |
2011年 | 36篇 |
2010年 | 37篇 |
2009年 | 34篇 |
2008年 | 37篇 |
2007年 | 28篇 |
2006年 | 21篇 |
2005年 | 22篇 |
2004年 | 15篇 |
2003年 | 18篇 |
2002年 | 14篇 |
2001年 | 19篇 |
2000年 | 18篇 |
1999年 | 18篇 |
1998年 | 29篇 |
1997年 | 47篇 |
1996年 | 37篇 |
1995年 | 32篇 |
1994年 | 22篇 |
1993年 | 20篇 |
1992年 | 12篇 |
1991年 | 14篇 |
1990年 | 13篇 |
1989年 | 24篇 |
1988年 | 21篇 |
1987年 | 15篇 |
1986年 | 16篇 |
1985年 | 11篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1955年 | 1篇 |
1952年 | 1篇 |
1948年 | 1篇 |
排序方式: 共有878条查询结果,搜索用时 31 毫秒
1.
2.
3.
Hausegger KA; Cragg AH; Lammer J; Lafer M; Fluckiger F; Klein GE; Sternthal MH; Pilger E 《Radiology》1994,190(1):199
4.
5.
6.
7.
8.
L Biancone M Boirivant S Fais G L Ricci R Paganelli F Pallone 《Clinical and experimental immunology》1991,83(3):401-406
We tested the hypothesis that serum factors present in Crohn's disease interfere with the process of lymphocyte activation. The mitogen-induced proliferation and the expression of early activation antigens by normal lymphocytes cultured in the presence of either Crohn's disease sera or sera from different controls were evaluated. The mitogen-induced proliferation was significantly impaired in the presence of Crohn's disease sera. These sera markedly inhibited the mitogen-induced interleukin-2 receptor (IL-2R) expression (48% inhibition), while the effect of sera on the expression of the transferrin receptor and the 4F2 antigen was much less pronounced. Diafiltration experiments showed that the inhibitory effect was confined to a 30-50-kD serum fraction. Such a serum property was not related to the patients' disease activity and disappeared after surgical removal of the affected bowel. The capability of inhibiting the mitogen-induced IL-2R expression was not restricted to Crohn's disease and was observed with sera from other inflammatory and neoplastic gastrointestinal disorders. This study indicates that a marked inhibition of the IL-2R is a mechanism underlying the immunosuppressive property of the serum in Crohn's disease and in other gastrointestinal conditions. 相似文献
9.
10.
CP Schaecher KA Groesch 《American journal of reproductive immunology (New York, N.Y. : 1989)》2006,55(6):405-405
Background: Control of mRNA stability is an essential regulatory process in eukaryotic gene expression. HuR, a 3'UTR mRNA binding protein, can protect AU-rich mRNA from degradation in response to stresses. PlGF, an angiogenic growth factor, contains two consensus AU-rich sites suggesting that under normal conditions HuR may protect PlGF mRNA from degradation. Trophoblast expression of PlGF is significantly decreased in preeclampsia and by hypoxia in vitro . We hypothesize that decreased levels of cytoplasmic HuR may contribute to decreased PlGF expression in hypoxic and preeclamptic trophoblast.
Methods: Western blots were used to determine relative effects of in vitro hypoxia on HuR protein expression and subcellular localization in trophoblast. Immunohistochemistry was used to compare HuR expression patterns in trophoblast of preeclamptic and normal placentae.
Results: Cytoplasmic expression of HuR was decreased 1.4 fold in the cytoplasm and 1.2 fold in the nucleus of JEG3 cells. A shift in HuR was more apparent in primary trophoblast with a greater than 2-fold decrease in the cytoplasm and a 1.4 fold decrease in the nucleus following 24 hr of hypoxia. Immunohistochemical analyses detected HuR expression in near term trophoblast in situ . However, this technical approach did not detect a significant change in HuR expression between normal and preeclamptic trophoblast.
Conclusions: HuR expression is decreased in hypoxic trophoblast, at least in vitro , which may provide a causal link to decreased PlGF mRNA expression. Down regulation of trophoblast PlGF expression is thought to contribute to the pathophysiology associated with preeclampsia including the relative lack of perfusion of the placenta and systemic renal effects. 相似文献
Methods: Western blots were used to determine relative effects of in vitro hypoxia on HuR protein expression and subcellular localization in trophoblast. Immunohistochemistry was used to compare HuR expression patterns in trophoblast of preeclamptic and normal placentae.
Results: Cytoplasmic expression of HuR was decreased 1.4 fold in the cytoplasm and 1.2 fold in the nucleus of JEG3 cells. A shift in HuR was more apparent in primary trophoblast with a greater than 2-fold decrease in the cytoplasm and a 1.4 fold decrease in the nucleus following 24 hr of hypoxia. Immunohistochemical analyses detected HuR expression in near term trophoblast in situ . However, this technical approach did not detect a significant change in HuR expression between normal and preeclamptic trophoblast.
Conclusions: HuR expression is decreased in hypoxic trophoblast, at least in vitro , which may provide a causal link to decreased PlGF mRNA expression. Down regulation of trophoblast PlGF expression is thought to contribute to the pathophysiology associated with preeclampsia including the relative lack of perfusion of the placenta and systemic renal effects. 相似文献